The retrofit strategy of the SFOBB is broken down into six major components:

East span interim retrofit

West approach

West span

West Viaduct

Yerba Buena island tunnel.

Replacement of the SFOBB East Span

BACKGROUND:This project is to retrofit the San Francisco- Oakland Bay Bridge (SFOBB) to current seismic safety standards and to provide post-earthquake "lifeline " service. As a lifeline route, the state would use the bridge to provide a high level of post-quake transportation service for emergency response and support for the region's economy. SFOBB is part of the Interstate 80 spanning San Francisco Bay; SFOBB extends 4.7 miles from San Francisco to Oakland on the east through Yerba Buena Island, which serves as an anchorage at mid point. The original bridge span is about 60 years old. Each deck of the bridge has five traffic lanes in each direction with no shoulders and the SFOBB carries about 280,000 vehicles per day.
The east span is a double deck steel cantilever truss bridge and sustained significant damage in the 1989 Loma Prieta earthquake.
The west span consists of twin, end-to-end suspension bridges and a three span continuous truss structure at the San Francisco end of the bridge. These structures extend from the San Francisco anchorage to the anchorage on Yerba Buena Island.

SEISMIC RETROFIT STRATEGY:The retrofit strategy of the SFOBB is broken down into six major components:

East span interim retrofit

West approach

West span

West Viaduct on Yerba Buena Island

Yerba Buena island tunnel.

Replacement of the East Span (the replacement bridge will be discussed later).

East span interim retrofit: Encompasses the full east span bridge from Yerba Buena island to Oakland, including the viaduct connecting the bridge to the tunnel. The east span interim retrofit will strengthen the bridge to withstand a likely earthquake, but not a Maximum Credible Earthquake. The interim retrofit will provide increased safety until the new east span is build. The interim retrofit will consist of adding reinforcement to strengthen bridge sections in critical areas, replacing rivets with high strength bolts, adding concrete collars around specific columns and seismic upgrades throughout the bridge.

West approach: Bounded by the 5th street and the and Francisco cable anchorage structure. Reconstruct the main line interstate 80 and on- and off-ramps in San Francisco, including modification to the ramps at the Transbay Transit terminal.